1. Field of the Invention
The present invention relates to an improvement in a battery connecting structure of a portable electronic apparatus of a wrist portable electronic timepiece, a heart beat transmitter of a heart beat measuring apparatus or the like.
2. Description of the Prior Art
JP-A-7-169451 discloses a battery connecting structure of an electronic timepiece in which a battery lead terminal is constituted by a pivotable structure in which one end thereof is provided with a portion brought into contact with a battery by constituting a fulcrum in the vicinity of a battery containing portion of a main plate and the other end thereof is provided with a portion brought into contact with a circuit board, and when the battery is contained in the containing portion, the battery lead terminal is pressed to be brought into contact with the circuit board. According to the battery connecting structure of the background art, there is achieved an effect that a screw for fixing the battery lead terminal is not needed. However, the battery connecting structure of the background art poses a problem that the battery connecting structure is applicable only to a battery lead terminal having a shape capable of adopting a pivotable structure.
FIG. 5 of JP-A-7-218659 discloses a battery connecting structure in which an electrode plate is directly fixed to a circuit board by press-fitting both end portions of the electrode plate into a locking hole board at the circuit board to be locked thereby. In sum, the battery connecting structure of the second background art is characterized in that in a battery connecting structure of a portable electronic timepiece directly fixing the minus battery terminal to the circuit board by utilizing the both end portions of the minus battery terminal comprising an elastic thin plate spring and the locking hole bored at the circuit board, the both end portions of the minus battery terminal are press-fitting portion directly press-fitted to the locking holes. However, there is a drawback that since the both end portions of the minus battery terminal are directly press-fitted to the circuit board per se to be fixed thereby, it is difficult to sufficiently ensure a press-fitting margin, further, since the both end portions of the minus battery terminal are brought into contact with the circuit board normally comprising a glass epoxy member, there poses a problem that harmful glass fiber powders are liable to be produced by abrasing to wear the circuit board by vibration, impact or the like of a product.
Hence, in order to resolve the problems, there is developed a battery connecting structure shown in FIG. 1 through FIG. 3 of JP-A-7-218659. The battery connecting structure of the third background art is a battery connecting structure in which a circuit board is mounted to a housing, the circuit board is mounted with a minus battery terminal having a board contact spring and a contact spring brought into contact with a battery, a locking portion is formed at at least one end portion of the minus battery terminal, and the minus battery terminal is fixed to the housing by locking the locking portion by a hold portion of the housing.
The battery connecting structure of the third background art is a simple structure. However, a digital wristwatch adopting the battery connecting structure of the third background art poses the following problem. That is, the housing needs to be formed with a locking hole for locking the locking portion of the electrode plate by the hold portion of the housing and therefore, an extra space is needed for the housing, and owing to the constitution of arranging a connector on an inner side of the locking hole and laying out a liquid crystal panel on the inner side to fix, product parting (display area) relative to a size of a product becomes very small. Further, it is necessary to make a minus electrode wiring region of the circuit board on a side of a battery face very large to bring about a layout which is disadvantageous in view of wiring. Since the wiring becomes disadvantageous, there is a high possibility of changing the board to a multilayered board, and in that case, not only the wiring becomes complicated but also the cost is increased. When the electrode wiring region is made to be small, there is needed an insulating sheet such that the circuit board wiring and the electrode plate are not short circuited. When the electrode plate is laid out on the inner side to make the wiring advantageous, the product parting becomes very small. Further, when the housing is provided with the locking hole for locking, the shape of the housing becomes complicated, the circuit board is pinched by the locking portion of the electrode plate and caught by the hold portion in the locking hole of the housing to fix and therefore, it is difficult to control a dimension of the locking portion of the electrode plate. Also integration is not easy by a repulsion force of the connector.
Further, in order to resolve the above-described problem of the second portable electronic apparatus, a fourth battery connecting structure has been developed and adopted in a digital timepiece on sale. As shown by FIG. 5, the fourth battery connecting structure of the background art is a battery connecting structure in which a circuit board 20 is provided with a locking hole 21 for coupling, hook-like catching portions 33a are provided at both ends of an electrode plate 30 constituting a minus terminal, the hook-like catching portions 33a are inserted into the locking hole 21 to penetrate head portions thereof, the minus terminal 30 is fixed to the circuit board 20 by catching jaws of the head portions by a back side of the circuit board 20.
In sum, the fourth portable electronic apparatus of the background art is characterized in that in the battery connecting structure of the portable electronic apparatus for directly fixing the battery minus terminal 30 to the circuit board 20 by utilizing the both end portions of the battery minus terminal 30 comprising an elastic thin plate spring and the locking hole 21 board at the circuit board 20, the both end portions of the battery minus terminal 30 are formed with a pair of the symmetrical hook-like catching portion 33a. The hook-like catching portion 33a is provided with a vertical portion having a length the same as a length of the locking hole 21 and the head portion substantially in a triangular shape formed at a front end of the vertical portion at a position of penetrating the locking hole 21 and therefore, also the above-described problems of the second and third battery connecting structures can almost be resolved.
However, according to the portable electronic apparatus of the fourth background art, there poses a problem that a shape of the hook-like catching portion 33a is complicated. Further, the length of the vertical portion of the hook-like catching portion 33a is determined in correspondence with a thickness of the circuit board 20 and therefore, when a separate product is intended to produce by changing the circuit board to the circuit board 20 having a different thickness, it is necessary to also change the electrode plate constituting the minus terminal 30. Further, there also poses a problem that the head portion substantially in the triangular shape of the hook-like catching portion 33a is projected from the back side of the circuit board 20, a product thickness is increased by an amount of projecting the head portion.
According to a first problem to be resolved by the invention, in a battery connecting structure of a portable electronic apparatus for directly connecting a minus battery terminal to a circuit board by utilizing both end portions of the minus battery terminal comprising an elastic thin plate and a locking hole bored at the circuit board, harmful glass fiber powders are prevented from being produced by abrasing and wearing the circuit board by vibration, impact or the like of a product and when changed to a circuit board having a different thickness, a change in the minus battery terminal is dispensed with.
According to a second problem to be resolved by the invention, in a portable electronic apparatus for directly connecting a minus battery terminal to a circuit board by utilizing both end portions of the minus battery terminal comprising an elastic thin plate and a locking hole bored at the circuit board, a portable electronic apparatus having a simple structure and low cost is provided.